OK, there seems to still be a certain amount of confusion about the amount of "smokiness" imparted to the food in a smoker, and temps.

The 140° mark is the point where the protein myoglobin will denature, and will no longer "cure" or change color with additional NO2 from the smoke. This stops the formation of the smoke ring.

It does NOT stop the ability of food to take on additional flavor from the smoke however.

On edit: And yes, moisture in the initial phase of the smoking process WILL increase the rate of smoke ring formation

The above is scientific fact. The below is my observations/opinion:

The smoke ring is said not to impart much flavor, but in fact it MUST impart some change in flavor, as it's actually a cure in the first 1/4" or so of the food. In a brisket or butt, this would matter little, but in ribs, it will result in a more "hammy" flavor.

Contradicting evidence cheerfully encouraged!

Below is a paper referring to some of the info I have presented.
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Smoke Ring in Barbeque Meats
How to Get That Coveted Pink Ring With Your Cooking
by Joe Cordray

Slow cooked barbecue meats often exhibit a pink ring around the outside edge of the product. This pink ring may range from 1/8 inch to 1/2 inch thick. In beef the ring is a reddish-pink and in pork, chicken and turkey it is bright pink. This pink ring is often referred to as a "smoke ring" and is considered a prized attribute in many barbecue meats, especially barbecue beef briskets. Barbecue connoiseurs feel the presence of a smoke ring indicates the item was slow smoked for a long period of time. Occasionally consumers have mistakenly felt that the pink color of the smoke ring meant the meat was undercooked. To understand smoke ring formation you must first understand muscle pigment.

Myoglobin is the pigment that gives muscle its color. Beef muscle has more pigment than pork muscle thus beef has a darker color than pork. Chicken thighs have a darker color than chicken breast thus chicken thigh muscle has more muscle pigment (myoglobin) than chicken breast tissue. A greater myoglobin concentration yields a more intense color. When you first cut into a muscle you expose the muscle pigment in its native state, myoglobin. In the case of beef, myoglobin has a purplish-red color. After the myoglobin has been exposed to oxygen for a short time, it becomes oxygenated and oxymyoglobin is formed. Oxymyoglobin is the color we associate with fresh meat. The optimum fresh meat color in beef is bright cherry red and in pork bright grayish pink. If a cut of meat is held under refrigeration for several days, the myoglobin on the surface becomes oxidized. When oxymyoglobin is oxidized it becomes metmyoglobin. Metmyoglobin has a brown color and is associated with a piece of meat that has been cut for several days. When we produce cured products we also alter the state of the pigment myoglobin. Cured products are defined as products to which we add sodium nitrate and/or sodium nitrite during processing. Examples of cured products are ham, bacon, bologna and hotdogs. All of these products have a pink color, which is typical of cured products. When sodium nitrite is combined with meat the pigment myoglobin is converted to nitric oxide myoglobin which is a very dark red color. This state of the pigment myoglobin is not very stable. Upon heating, nitric oxide myoglobin is converted to nitrosylhemochrome, which is the typical pink color of cured meats.
When a smoke ring develops in barbecue meats it is not because smoke has penetrated and colored the muscle, but rather because gases in the smoke interact with the pigment myoglobin. Two phenomenon provide evidence that it is not the smoke itself that causes the smoke ring. First, it is possible to have a smoke ring develop in a product that has not been smoked and second, it is also possible to heavily smoke a product without smoke ring development.

Most barbecuers use either wood chips or logs to generate smoke when cooking. Wood contains large amounts of nitrogen (N). During burning the nitrogen in the logs combines with oxygen (O) in the air to form nitrogen dioxide (NO2). Nitrogen dioxide is highly water-soluble. The pink ring is created when NO2 is absorbed into the moist meat surface and reacts to form nitrous acid. The nitrous acid then diffuses inward creating a pink ring via the classic meat curing reaction of sodium nitrite. The end result is a "smoke ring" that has the pink color of cured meat. Smoke ring also frequently develops in smokehouses and cookers that are gas-fired because NO2 is a combustion by-product when natural gas or propane is burned.

Let’s review the conditions that would help to contribute to the development of a smoke ring. Slow cooking and smoking over several hours. This allows time for the NO2 to be absorbed into and interact with the meat pigment.

Maintain the surface of the meat moist during smoking. NO2 is water-soluble so it absorbs more readily into a piece of meat that has a moist surface than one which has a dry surface. Meats that have been marinated tend to have a moister surface than non-marinated meats. There are also a couple of ways that you can help to maintain a higher humidity level in your cooker; 1. Do not open and close the cooker frequently. Each time you open it you allow moisture inside to escape. 2. Put a pan of water on your grill. Evaporation from the water will help increase humidity inside the cooker.

Generate smoke from the burning of wood chips or wood logs. Since NO2 is a by-product of incomplete combustion, green wood or wetted wood seems to enhance smoke ring development. Burning green wood or wetted wood also helps to increase the humidity level inside the cooker.
A high temperature flame is needed to create NO2 from nitrogen and oxygen. A smoldering fire without a flame does not produce as much NO2. Consequently, a cooker that uses indirect heat generated from the burning of wood typically will develop a pronounced smoke ring. Have fun cooking. A nice smoke ring can sure make a piece of barbecued meat look attractive.

About the Author:

Joe Cordray is the Meat Extension Spe******t at Iowa State University’s nationally renowned Meat Lab, located in Ames, IA. He has been writing for The BBQer since Fall of 2001

I think it does change the flavor as you are "curing" the meat as you cook it. I agree that the food will continue to absorb smoke flavor as long as it is in the smoke.

I try to not over smoke ribs as a rule and usually use 3-2-1 to prevent that. With beef ribs I don't mind a deeper color change. Of course that is my personal preference and everyone needs to discover what works for them. I also find that I end up changing techniques and recipes based on feedback from the folks that eat my Q!

Thanks for the info, I smoked the whole time before I found this site, I had meat that was good, but bitter with smoke. Now I put some chunks on in the begining, let them burn down, and add a couple more and thats it. Food started tasting alot better since I have been doing it this way.

I will still adhere to the 140Âº rule although somewhat modified. Too many times I hear people complain of a "over smoked" taste when they do their bar-b-que. Possibly "too much" smoke or "too heavy" a smoke was done in the first place. I tend to smoke alot during the temps up to 140Âº, then throw a chunk in each hour of remaining time.
It really boils down to your own tolerence for a smokey flavor, kinda like hot sauce I guess (some people are whimps ) I find the rule works for me, you'll have to make your own decision whether it does for you. I do feel if you continue to add smoke thru out the whole cooking process, you will continue to add flavore to the meat, atleast the outside of the meat.

Oh nothing wrong with more flavor. As stated I just feel it will end up on the outside of the meat only and not work it way into the interior so much. If it stays only on the surface, then this is where "some folks" will find that over smoked flavor. Others should not have a problem.
Time to prep the chuck roast

Rich, here again is a personal preference thing. I personally like some things with a heavy smoke. So I smoke longer. When I do smoke longer I tend to use a lighter wood though.
I did over smoke something once and have not done that again. Its all how you the cook and the one who is going to be eating it prefer your food.

Ok, I am going to ask a really stupid question on this topic. How does cooking with wood only not cause the over smoked flavors your talking about. I tend to use more wood to keep my fire going for longer times than just charcoal. I guess being a newbie I just don't get it.

the best thing to do in this case is preburn the wood, some even lite it and add hot coals to the firebox as needed. Preburn in a chimnea or barrel or some thing then put it out and save for future use. Hope this helps!!!!!!!

Thanks Smokeys. I don't want to carry on to much on this thread, but what about bark? I have been told to remove it as it will make the meat sooty, and I have had some tell me they cut it fresh and burned it green with bark.

Sorry Flash I was not referring to your food in particular, but just that many folks who say they don't like "too much smoke" may have based that on something that had some creosote.... like one of my early runs!!!!!

I think alot of this has to do with pit temps as well. A rocket hot pit will take alot of nasties out of the equation real fast. Preburning burns them off before they hit the pit. I'd think in an electric, you'd be asking for trouble. I don't bother with the bark, it's minimal on the splits I use, and I usually have a decent bed of HOT lump in the ECB.

I would not use green wood tho. But if ya toss it in a blast furnace... it would burn off the crap in a hurry. If ya preburn green wood to char- it's "seasoned". I just would not do it in my firebox.